The present invention relates to an information input apparatus having a manual implement such as a remote controller for controlling a television set. Further, the information input apparatus may also be used in a game machine having a display, a personal computer, and a word processor for menu operations and pointing operation. Moreover, the information input apparatus can be used for input of figures and hand-written characters, and for manipulation of a graphic object on a screen.
There are various types of conventional manual information input tools such as a digitizer composed of a stylus and a tablet, and a mouse pointing implement. In operation of the digitizer, the stylus and the tablet exchange an electromagnetic signal or other signals therebetween to detect an absolute position of the stylus, which is inputted into a computer. The mouse pointing implement is manually moved over a pad or other flat surface to input incremental displacement information into the computer. The digitizer detects an absolute position of the stylus, whereas the mouse implement detects a relative displacement thereof. However, the digitizer and the mouse implement each requires that the tablet or the pad be disposed on a working table. Therefore, these manual tools suffer from limited working condition and space.
There is another type of a manual input tool called an "optical pointer" which can be operated freely of a working table. The optical pointer is disclosed in Japanese Patent Application Laid-Open No. 6-59807. The optical pointer having a light source is manually handled, while a computer is provided with a video camera for capturing the light source to detect a position of the optical pointer. A cursor displayed on a screen of the computer machine is displaced according to the detected position of the optical pointer. The optical pointer is captured by the video camera to detect the absolute position of the light source. Therefore, the optical pointer is an absolute position detector like the digitizer. However, the video camera is too complex for use in a handy input tool. In a practical sense, absolute detection is not needed for cursor manipulation and menu selection. Relative displacement information may be sufficient in most applications as provided by the mouse pointing implement.